The present invention relates generally to the field of paper-based food containers, and more particularly to frozen food trays, ice cream containers, gable top containers, beverage cups, food cartons and the like having press-applied coatings thereon.
Paper-based food containers have customarily been formed from paperboard extruded with wax or a polymer layer, such as polyethylene, polypropylene or polyethylene terephthalate (PET). Additional coatings have been developed for, among other things, rendering the food cartons resistant to grease and moisture and for preventing ink-printed graphic designs from leaching into the food contained therein.
For example, U.S. Pat. No. 4,595,611 to Quick et al. discloses an ink-printed ovenable food container comprising a layer of ink printed on the food contact side of a paperboard substrate and a layer of polyester resin atop the ink for preventing the ink from migrating into the food. U.S. Pat. No. 4,463,029 to Nishijima et al. describes a baking tray sheet which is heat resistant and may be used in both microwave and conventional ovens. The baking tray sheet has a base of paper or cardboard coated with a layer composed of polyvinyl alcohol and/or starch and a water-resisting agent. Atop this layer is an additional coating of silicone. U.S. Pat. No. 4,469,258 to Wright et al. discloses a tray formed from paperboard or plastic. The paperboard tray may have extruded thereon PET, polypropylene, acrylics or hot melt materials to render the tray resistant to water, oils and fats. U.S. Pat. No. 4,418,119 to Morrow et al. discloses an ovenable board formed from paper or paperboard and coated with a layer of polyvinyl alcohol and a silicone. U.S. Pat. No. 4,456,164 to Foster et al. describes an ovenable container having a base of molded pulp or pressed paperboard having a layer of polymeric material bonded thereto in a secondary process.
Due to the relative expense of polymeric material, polymer-extruded paperboard food containers as described above are undesirably costly to fabricate. Additionally, because of the polymers extruded onto the paper material, these food cartons are not readily recyclable.
It is, therefore, an object of the present invention to provide a food container having a paperboard base with liquid coatings press-applied thereon.
It is another object of the present invention to provide a food container having a paperboard base with coatings resistant to grease and/or moisture issuing from foods.
It is still another object of the present invention to provide a food container having a paperboard base with coatings that remain resistant to grease and/or moisture through a broad range of temperatures.
It is yet still another object of the present invention to provide a food container that may be capable of being recycled.